The growth of local and wide area networks based on Ethernet technology has been an important driver for cabling offices and homes with structured cabling systems having multiple twisted wire pairs. The structured cable is also known herein as communication cabling and typically comprises four twisted wire pairs. In certain networks only two twisted wire pairs are used for communication, with the other set of two twisted wire pairs being known as spare pairs. In other networks all four twisted wire pairs are used for communication. The ubiquitous local area network, and the equipment which operates thereon, has led to a situation where there is often a need to attach a network operated device for which power is to be advantageously supplied by the network over the network wiring. Supplying power over the network wiring has many advantages including, but not limited to; reduced cost of installation; centralized power and power back-up; and centralized security and management. A good portion of modern office telephone systems are implemented as voice over Internet protocol (VoIP) telephones, powered by PoE, thus providing for the above mentioned benefits.
The IEEE 802.3af-2003 standard, published by the Institute of Electrical and Electronics Engineers, Inc, New York, whose entire contents are incorporated herein by reference, is addressed to powering remote devices over an Ethernet based network. Power can be delivered to the powered device (PD) either from a power sourcing equipment (PSE) associated with the switch/hub known as an endpoint PSE or alternatively via a midspan PSE connected between the switch/hub equipment and the PD. A PSE as used in this document may supply power over Ethernet to one or more ports, and a single PSE is defined as power sourcing equipment contained in a single chassis. In either case power is delivered over a set of two twisted pairs of wires. PoE ports of either a midspan PSE or an endpoint PSE can typically be remotely controlled from a management station. In one embodiment, each port may be controlled to one of an enabled state, in which a powered device is automatically detected if attached thereto and powered, and a disabled state in which detection does not occur. In yet another embodiment each port in a disabled state performs detection on a periodic basis, however a detected PD is not powered. The popularity of the above mentioned standard has led to a demand for increased power to the PD, resulting in the formation of the IEEE P802.3 at DTE Power Enhancements Task Force.
PDs comprise a whole host of data terminal units for which power is advantageously delivered via the communication cabling. Specific examples of PDs include VoIP telephones, wireless access points (WAPs) and access control devices.
Wiring of a system according to the IEEE 802.3 standard, published by the Institute of Electrical and Electronics Engineers, Inc, New York the entire contents of which is incorporated herein by reference, typically comprises cables terminated at a work area in a telecommunications outlet/connector (TO) as defined by TIE/EIA 568 published by the Telecommunications Industry Association 2001 of Arlington, Va., and by ISO/IEC 11801 published by the International Organization for Standardization and the International Electrotechnical Commission, Geneva, Switzerland, the entire contents of both of which are incorporated herein by reference. The TO is connected via horizontal cabling, optionally through at most one each of a transition or consolidation point, a user patch panel and an equipment patch panel to the common equipment which typically comprises a switch/hub or bridge. Optionally, a midspan device may be connected between the common equipment and one user patch panel to provide power. The connections between the common equipment and the TO may be changed by rearranging patch cords connected between any of the common equipment, the user patch panel and the equipment patch panel. In an installation in which both a user patch panel and an equipment patch panel are provided, or a midspan device and a user patch panel are provided, the connections between the common equipment and the TO are typically changed by rearranging patch cords between the equipment patch panel or the midspan device and the user patch panel.
Access control systems are often installed to enable control accessed by authorized individuals and deny access to others. Electronically implemented access control systems enable access to such premises without requiring a human guard. Access control systems may be implementation, without limitation, by smart cards, bar coded access strips, or punch in codes, thus enabling access at any hour or day. Access control systems are typically supplied as stand alone systems, controlling and recording access events.
Office hours and business days are well known features of the work week. Office security is improved by a scheduled disabling of PoE ports during hours and/or days which are not scheduled for work, thereby disabling WAPs and optionally PoE powered telephones, when the office is not populated. Additionally, power can be saved by disabling PoE ports during non-business days, and/or non-office hours. Such a scheduled disabling is preferably accomplished from a management station operable by authorized personnel. Unfortunately, a user who unexpectedly requires the use of a PD, such as a WAP, which is connected to a scheduled disabled port finds the PD inoperable irrespective of the user being granted access by the access control system. The user may not have access to the management station which has set the port to be disabled.
It is further desirable to maximize the amount of power saved, by shutting down power to unused PoE ports whenever practicable.